マーチソン隕石の個々のアミノ酸の炭素同位体組成
M H Engel1, S A Macko, J A Silfer
1School of Geology and Geophysics, University of Oklahoma, Norman 73019, USA.
Nature
|November 1, 1990
まとめ
マーチソン隕石のような小惑星からの有機化合物は,炭素13濃縮を示し,地球外の起源を示しています. 非ラセミックなアラニンは,生命が出現する前に,太陽系初期にプレバイオティックキラル分子が存在していたことを示唆しています.
科学分野:
- 天体生物学 アストロバイオロジー
- オーガニック・ジオケミストリー オーガニック・ジオケミストリー
- 宇宙化学 (コスモケミストリー)
背景:
- 初期の地球上のプレバイオティックな有機物質は,小惑星や彗星のような地球外の源から生まれた可能性が高い.
- 炭酸性隕石は,プリバイオティクスの合成経路と初期の地球の有機組成についての洞察を提供します.
- 以前の研究では,隕石のアミノ酸における一般的な13C濃縮が認められたが,個々の化合物の分析は欠けていた.
研究 の 目的:
- マーチソン隕石内の個々のアミノ酸の炭素13 (13C) 含有量を決定するために.
- 隕石で見つかった特定のアミノ酸の地球外起源と潜在的プレバイオティクスの重要性を調査する.
- 太陽系初期に存在した光学活性有機化合物の存在を調査する.
主な方法:
- マーチソン炭酸隕石から抽出した個々のアミノ酸の分析.
- 安定同位体比質量スペクトロメトリーは,特定のアミノ酸の13C含有量を測定します.
- アミノ酸,特にアラニンのエナティオメリック組成を評価するためのキラル分析.
主要な成果:
- マーチソン隕石の分析されたすべてのアミノ酸は,13Cの濃縮を示し,その地外起源を確認した.
- アラニンは非ラセミックであることが判明し,D-およびL-エナティオマーの両方で明確な13C濃縮が観察されました.
- アラニンエナティオメアにおける観測された13C濃縮は,地上の汚染ではなく,原生キラリティを示唆しています.
結論:
- 隕石のアミノ酸は,13C濃縮により,地球外生命体であることが確認されています.
- アラニンの非ラセミックな性質は,太陽系初期の光学的に活性な有機物質の存在を示しています.
- これらの発見は,キラル分子が地球上の生命より前に存在し,その起源に影響を与えた可能性があるという仮説を支持する.
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